Aqueous coating composition based on a binder mixture as base coat

Abstract

The invention relates to an aqueous coating composition based on a combination of aqueous binders and crosslinker, to a process for preparing it and to use for single-coat or multi-coat paint systems, especially coatings having anti-stonechip properties.

1. Aqueous coating compositions comprising:
 an aqueous binder mixture A) comprised of: 
 A1) 25% to 70% by weight of a secondary, hydroxy-functional polyacrylate dispersion or a secondary, hydroxy-functional polyacrylate emulsion having a solids content of between 20% and 60% by weight, 
 A2) 5% to 50% by weight of an aliphatic polyurethane dispersion having a solids content of between 25% and 60% by weight, and 
 A3) 20% to 70% by weight of a hydroxy-functional polyester-polyurethane dispersion composed to an extent of at least 75% by weight of a polyester of molecular weight 500 to 2,500 g/mol and having a solids content of between 25% and 55% by weight,
 wherein the percentages by weight of A1), A2) and A3) are based on the aqueous binder mixture A); and 
 
 B) at least one crosslinker, 
 
       necessarily including one component A1) and/or A3) in an amount of at least 35% by weight. 
     
     
       2. Aqueous coating compositions according to  claim 1 , having an organic solvent content of 2% to 12% by weight. 
     
     
       3. Aqueous coating compositions according to  claim 1 , wherein component B) is amino crosslinker resin(s). 
     
     
       4. Aqueous coating compositions according to  claim 1 , wherein component B) is a combination of amino crosslinker resins and polyisocyanates. 
     
     
       5. Aqueous coating compositions according to  claim 1 , further comprising
 C) one or more dispersions selected from the group consisting of polyurethane dispersions C1), polyacrylate emulsions C2) or polyurethane-polyacrylate dispersions C3). 
 
     
     
       6. Aqueous coating compositions according to  claim 5 , comprising
 A) 15% to 90% by weight of an aqueous binder mixture, 
 B) 5% to 40% by weight of at least one crosslinker and 
 C) 5% to 65% by weight of one or more dispersions selected from the group consisting of polyurethane dispersions C1), polyacrylate emulsions C2) or polyurethane-polyacrylate dispersions C3), 
 the percentages for A), B) and C) adding up to 100% by weight. 
 
     
     
       7. Aqueous coating compositions according to  claim 1 , further comprising
 C) one or more dispersions selected from the group consisting of polyurethane dispersions C1), polyacrylate emulsions C2) or polyurethane-polyacrylate dispersions C3), and 
 D) a water-dilutable, hydroxy-functional polyester resin. 
 
     
     
       8. Aqueous coating compositions according to  claim 7 , comprising
 A) 15% to 89.5% by weight of an aqueous binder mixture, 
 B) 5% to 40% by weight of at least one crosslinker and 
 C) 5% to 65% by weight of one or more dispersions selected from the group consisting of polyurethane dispersions C1), polyacrylate emulsions C2) or polyurethane-polyacrylate dispersions C3) and 
 D) 0.5% to 30% by weight of a water-dilutable, hydroxy-functional polyester resin, the percentages for A), B), C) and D) adding up to 100% by weight. 
 
     
     
       9. Aqueous coating compositions according to  claim 5 , wherein component C) is a physically drying dispersion. 
     
     
       10. Aqueous coating compositions according to  claim 1 , further comprising
 D) a water-dilutable, hydroxy-functional polyester resins. 
 
     
     
       11. Aqueous coating compositions according to  claim 10 , comprising
 A) 30% to 94.5% by weight of an aqueous binder mixture, 
 B) 5% to 40% by weight of at least one crosslinker and 
 D) 0.5% to 30% by weight of a water-dilutable, hydroxy-functional polyester resin, the percentages for A), B) and D) adding up to 100% by weight. 
 
     
     
       12. Aqueous coating compositions according to  claim 7 , wherein component D) has acid numbers in the range from 25 to 75 mg KOH/g solids and/or hydroxyl group contents of 2.5% to 10% by weight and/or molecular weights in the range from 750 to 5000 g/mol and/or fatty acid constituents in amounts of 15% to 50% by weight. 
     
     
       13. Anti-chip base coats comprising the aqueous coating compositions according to  claim 1 . 
     
     
       14. Paint system comprising a substrate and at least one coat composed of aqueous coating compositions according to  claim 1 . 
     
     
       15. The paint system according to  claim 14 , wherein the substrate is selected from the group consisting of plastics, wood, metal, mineral substrates, textiles, leather, glass and combinations thereof.